SEMESTER 2024 - SUMMER
26.03.2024
Benjamin Knorr
Nordita, Stockholm University and KTH Royal Institute of Technology
Asymptotic Safety meets field redefinitions
Asymptotic Safety is an approach to quantum gravity that solely relies on quantum field theory - it posits that gravity can be quantised by a nonperturbative fixed point of its renormalisation group flow. This rather simple idea is complicated by the fact that in quantum field theory, field redefinitions can be performed without changing physical predictions, encoded for example in scattering amplitudes. As a consequence, only so-called essential couplings need to show such a fixed point - these are the combinations of couplings that are invariant under such redefinitions. In this talk, after a general introduction to Asymptotic Safety, I will discuss recent developments in how to treat the freedom of field redefinitions within nonperturbative renormalisation group flows. In particular, I will show how we can wield this freedom to simplify computations enormously so that more refined approximations can be investigated, consequently improving the accuracy of predictions.
Slides
09.04.2024
Rene Poncelet
Institute of Nuclear Physics PAN, Kraków
Precision phenomenology with heavy-flavour jets at the LHC
Jets are a staple of the research program at high-energy hadron colliders. As suitably defined sets of highly-energetic particles, they constitute a useful tool to establish a link between Quantum Chromodynamics (QCD) of quarks and gluons and the realm of actual strongly-interacting particles, baryons and mesons. Besides the general importance of jets for collider phenomenology, there is a growing interest in studying jet substructure in order to disentangle various QCD effects governing jet dynamics. Final states with jets identified to originate from heavy quarks play a vital role, for example, in understanding the process of heavy-quark fragmentation and the contents of protons at high energy. In this talk I will discuss fixed-order NNLO QCD phenomenology, comparisons thereof to data and infrared-safe flavoured jet algorithms, a non-trivial ingredient in defining useful collider observables.
Slides
23.04.2024
Nicolas Bernal
New York University Abu Dhabi
New Avenues For Dark Matter Production
The existence of nonbaryonic dark matter (DM) in the Universe is compelling, as suggested by astrophysical and cosmological observations. The most commonly assumed production mechanism for DM in the early universe corresponds to the weakly interacting massive particle (WIMP) paradigm, in which DM has mass and couplings at the electroweak scale. However, the current null experimental results and severe constraints on the natural parameter space are forcing us to search beyond the standard WIMP paradigm. In this talk, I will review alternative DM production mechanisms in the early universe, both thermal and non-thermal, like the FIMP and the SIMP paradigms. The possible impact of alternative non-standard cosmological scenarios will also be analyzed. Finally, experimental avenues for DM detection are discussed